Pixelated-LED chips and related methods are disclosed. A pixelated-LED chip includes an active layer with independently electrically accessible active layer portions arranged on or over a light-transmissive substrate. The active layer portions are configured to illuminate different light-transmissive substrate portions to form pixels. Various enhancements may beneficially provide increased contrast (i.e., reduced cross-talk between pixels) and/or promote inter-pixel illumination homogeneity, without unduly restricting light utilization efficiency. In some aspects, an underfill material with improved surface coverage is provided between adjacent pixels of a pixelated-LED chip. The underfill material may be arranged to cover all lateral surfaces between the adjacent pixels. In some aspects, discontinuous substrate portions are formed before application of underfill materials. In some aspects, a wetting layer is provided to improve wicking or flow of underfill materials during various fabrication steps. Other technical benefits may additionally or alternatively be achieved.
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2. The pixelated-LED chip of claim 1, wherein the second underfill material is compositionally different from the first underfill material.
3. The pixelated-LED chip of claim 1, wherein the first underfill material and the second underfill material in combination cover an entirety of the lateral surfaces between the adjacent pixels.
4. The pixelated-LED chip of claim 1, wherein the electrical contacts of each pixel comprise an anode and a cathode, and the first underfill material is further arranged between the anode and the cathode of each pixel of the plurality of pixels.
5. The pixelated-LED chip of claim 1, wherein at least one of the first underfill material or the second underfill material comprises a light-altering or a light-reflecting material.
6. The pixelated-LED chip of claim 5, wherein the light-altering or light-reflecting material comprises light-altering or light-reflecting particles suspended in a binder.
7. The pixelated-LED chip of claim 6, wherein the light-altering or light-reflecting particles comprise titanium dioxide (TiO2) particles and the binder comprises silicone.
8. The pixelated-LED chip of claim 1, further comprising a substrate comprising a plurality of discontinuous substrate portions supporting the plurality of active layer portions, wherein each substrate portion comprises a light-transmissive material.
9. The pixelated-LED chip of claim 8, wherein the plurality of discontinuous substrate portions comprises silicon carbide (SiC) or sapphire.
10. The pixelated-LED chip of claim 8, wherein each substrate portion comprises a light injection surface and a light extraction surface, wherein the light injection surface is arranged between the active layer and the light extraction surface and the light extraction surface of each substrate portion comprises a plurality of protruding features and a plurality of light extraction surface recesses.
11. The pixelated-LED chip of claim 8, wherein each substrate portion comprises a light injection surface and a light extraction surface, wherein the light injection surface is arranged between the active layer and the light extraction surface, and the light extraction surface of each substrate portion comprises a textured surface.
12. The pixelated-LED chip of claim 1, further comprising a lumiphoric material on the plurality of pixels.
14. The method of claim 13, further comprising forming a plurality of anode-cathode pairs in conductive electrical communication with the plurality of active layer portions, and wherein the providing of the first underfill material further comprises applying the first underfill material between an anode and a cathode of each anode-cathode pair.
15. The method of claim 13, further comprising forming a plurality of protruding features and a plurality of light extraction surface recesses on a light extraction surface of each of the substrate portions.
16. The method of claim 13, further comprising texturizing a light extraction surface of each of the substrate portions.
17. The method of claim 16, wherein said texturizing the light extraction surface of each of the substrate portions comprises texturizing a surface of the substrate before forming the plurality of discontinuous substrate portions.
18. The method of claim 13, wherein the providing of at least one of the first underfill material or the second underfill material comprises applying underfill material between the discontinuous substrate portions from the top of the pixelated LED chip.
19. The method of claim 13, wherein the second underfill material is compositionally different from the first underfill material.
20. The method of claim 13, wherein at least one of the first underfill material or the second underfill material comprises a light-altering or a light-reflecting material.
21. The method of claim 20, wherein the light-altering or light-reflecting material comprises light-altering or light-reflecting particles suspended in a binder.
22. The method of claim 21, wherein the light-altering or light-reflecting particles comprise titanium dioxide (TiO2) particles and the binder comprises silicone.
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January 19, 2021
May 30, 2023
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